The antigenic reactive sites of native hen egg-white lysozyme will be delineated. Lysozyme will be cleaved enzymatically to yield fragments with intact disulfide bonds. The immunochemistry of the peptide fragments will be studied by a variety of inhibition and binding techniques. Disulfide peptides and "sufrace-simulation" peptides will be synthesized and studied. Antibodies to the sites will be prepared from antisera to lysozyme and by direct immunization with site-carrier conjugate. The specificity, binding affinity, restricted heterogeneity of the antibodies as well as their ability to inhibit the enzymic activity of lysozyme will be evaluated. The maturation and maintenance of the immune response to the antigenic sites and their relative immunodominance will be studied in rabbits and pigs.